Rock ptarmigans, a species designated by the government as a special national treasure, are at risk of disappearing from one of the bird's major habitats by the end of this century, scientists have said, citing global warming as the main cause.
Predicting a drastic decrease in the alpine plants in the species' habitat in the Northern Japanese Alps, a team of researchers from the Nagano Environmental Conservation Research Institute, the Forest Research and Management Organization, Kochi University, and Tokyo University of Agriculture, released their findings in an article carried on the website of British science journal BMC Ecology on July 10.
According to the Environment Ministry, indigenous rock ptarmigans, known as raicho in Japanese, live in high-altitude areas in the mountainous regions stretching along the prefectural borders between Niigata, Toyama, Nagano and Gifu.
The estimated population of the bird stood at about 3,000 in the 1980s, but the figure is now believed to have decreased to less than 2,000, concentrated mostly in the Northern and Southern Japanese Alps. Encroachments into the mountain range by foxes and Japanese martens, both predators of the bird, are also thought to have contributed to the population decrease.
The research team focused on how certain factors such as temperature and snowfall would affect alpine plants, which rock ptarmigans eat or use to make their nests, in the central and southern parts of the Northern Japanese Alps.
The team predicts that if global warming progresses at its current pace, the temperature in the area would rise by 2 C to 4 C between 2081 and 2100 and snowfall would decrease.
Climate change would shrink the rock ptarmigan's habitable zone to an area 0.4 percent of the bird's current habitat, based on alpine plant vegetation forecasts.
The team also learned that rock ptarmigans tend to live in areas where a variety of alpine plants grow, such as stone pines, which the species use for their nesting sites, and those that can withstand strong mountain winds.
"If the alpine plants die out, it would mean no more Rock ptarmigans," said Masanobu Hotta, 60, of the Nagano Environmental Conservation Research Institute. "We will probably need to take measures to protect the species, such as by moving birds to other areas."
The team will also research the impact of global warming on the Southern Japanese Alps and other habitats of the species.
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